Electric discharge tube



May 9, 1939. H. wI-:NDLIK ELECTRIC DISCHARGE TUBE Filed May ll, 1938ATTORNY Patented May 9, 1939 UNITED STATES ELECTRIC DISCHARGE TUBEHubert Wendlik, Prague,

signor to Westinghouse E turing Company, East ration of Pennsylvani InCzechoslovaki 4 Claims. A(Cl. 176-50) to discharge devices and ontainerof such discharge My invention relates especially to the c devices.

An object of the invention is to provide a discharge device having acontainer that is especially resistant to strong electric, chemical, andthermal effects in the vicinity of the electrodes.

Another object of the invention is to utilize ceramic material in thecontainer walls of the discharge device.

Other objects and advant will be apparent from th and drawing, in which:

Fig. 1 is a view in cross-section of a discharge device illustrating anembodiment of the invention in the container wall adjacent theelectrode.

Figs. 2, 3, 4, 5, 6, 8, and 9 are gures in crosssection that aremodications of the embodiment of the invention in Fig. 1.

Figs. 7 and 1Q are cross-sectional views of a discharge devicedisclosing modifications of the invention applied to the completecontainer.

It is generally known. that that part of the discharge. tubevwhere theelectrode is located is made from glass.

In developing the tubes it was found that the glass parts in thevicinity of the electrode are subject to strong electric, chemical, andthermal effects. Especially the hot electrodes, such as an incandescentcathode, necessitate the protection of the glass parts located close tothem.

Such protection is achieved by increasing the distance between the glassand the electrode by enlarging the tube so as to form a spherical shapeand locating the electrode in the center.

Or, a screening is made between glass and electrode, consisting of metalor insulating material.

Finally, there is a design using special glass or gas-tight ceramicmaterials that are resistant to the above mentioned influences.

An increase of the distance between glass and electrode offers thedisadvantage that the shape of the discharge tube has to be changed in away which makes it less eiilcient and desirable.

undesirable because it The use of screening is is diiicult to securelysupport the screening parts. orts occupy much space,

These screens and supp and special brackets are required, which makested.

the design too complica ase the price of the tube Special glasses increbecause of higher priced material and manudes, they are only partlysatages of the invention e following description facturing costs; besiisfactory.

As it was already mentioned, gas materials are used too, and theyspecial sealing.

It is known that ceramic materials are much more resistant to electric,chemical, and heat action in the space of discharge than glass.

Up to now the choice of these materials has tight ceramic do not requireI placi Czechoslovakia, aslectric & Manufac- Pittsburgh, Pa., a corpoa'.

Application May 11, 193

8, Serial No. 207,200 aMay 18, 1037 been limited, because the materialsthat were most "satisfactory from a manufacturing standpoint were notgas-tight.

According to the present invention, the above mentioned disadvantagesare overcome by reng the glass in the proximity of theelectrode by aceramic material which is made gas-tight by special sealing materials.

The following have been found to be the best sealing materials: enamels,metal surfacing, varnishes, impregnation (for example soaking in oils,waxes, fats, oils of a low evaporating pressure) and liquids.

'I'he choice of a sealing material depends on the type of the dischargetube and on the conditions in which it is to operate. As an example,mercury would be a suitable sealing material for tubes containingmercury.

When enamels are used, it is them on the outside of the tube, in orderto avoid exposure in the discharge space.

The metal coating for sealing is applied by the electroplating process;also by spraying and by dipping into a metal bath good results can beobtained.

'I'he current leads through the ceramic the sealing coatin ticles.

When enamel or metal coating is used, it is advisable, if no specialsealing is added, to make it stronger at those points where the currentleads are located.

When fusin advisable to a l DD y 20 25 to the electrodes are ledmaterial and are sealed by g itself or by special glass parintermediatemetal layers.

In Figs. 1 through 10 of the drawing, I have illustrated severalpossible applications of the invention. In Fig. 1 I have illustrateddiagrammatically an electrode 5 supported on the current lead 6. I'hiselectrode may take any desired form of the prior art including the typeof hot electrode previously mentioned that necessitates the protectionof the walls located close to it. The electrode 5 is enclosed by acup-shaped ceramic body 3 that is sealed by fusion to the glass wall ofthe vessel or container I at the point of sealing or fusion 2. A coating4 of enamel, metal coatings, or varnish, is applied to the outsidesurface of the ceramic cup-shaped body 3 by any of the means previouslymentioned. The lead or leads 6 pass through the ceramic material asdisclosed. In Fig. 2 the cup-shaped ceramic 4body has a projection orrim l that protrudes into the glass vessel l and has lateral extensionsfor making the seal 2 with the glass vessel I. The special advantage ofthis shape is that the ceramic prointermediate the seal 2 and thedisterminating on the active face of the modification is disclosed inwhich the ceramic projection I into the vessel I has an enlarged conicalshape 8 that acts to concentrate the discharge towards the activesurface of the electrode 5. The lateral projection from the ceramic bodyin this modification makes the seal 2 with the laterally. extending bodyof the glass portion of the vessel instead of the lateral ceramicextension being bent at right angles in Fig. 2 to make a seal withthetubular portion of the container. It will be noted that the enamel,metal coating; or varnish is made stronger at the exterior part 9 wherethe current lead passes through the ceramic material.

In Fig. 4 I have disclosed a modification of the invention in which theceramic body 3 has a tube-shaped prolongation extending upward from thebottom of the cup to support within its enclosure the electrode 5. Thisarrangement protects against heat losses. The sealing is done by meansof enamel, metal coating, or varnish. Additional glass particles I I areutilized for sealing the current lead or leads where-they pass throughthe ceramic body.

In Fig. 5, the modification discloses in place o the diagrammaticallyillustrated electrode 5, an electrode 5 comprising an inner metalcoating on the ceramic body. The current lead or leads Ii pass throughthe ceramic body and are first protected by a thickened portion of thesealing enamel, metal coating, or varnish t and then by cement containedin a base I2.

In Fig. 6 I have disclosed ing 5 similar to the coating 5 in Fig. 5 butit does not have the current lead 5 through the ceramic material. Theouter coating 4 in this figure is Yof metal which combines incombination with the inner metal coating 5 on the other side of theceramic material to form a condenser with the inner coating as anelectrode. The ceramic material in this modification preferably has ahigher dielectric content. As is materials can be manufactured with adielectric constant more than forty times higher than that of air. Thisarrangement makes it possible to have a very small electrode of a sizethat would not be possible when only glass is utilized.

In Fig. '7, I have disclosed an application of the design in Fig. l toboth ends of the tube so that they constitute a complete container for adischarge device. An opening I6 is located in this modification at theplace of the fusing seam 2 and can be used as tubulation or for anyother purpose desired. The sealing on the exterior of the ceramicportion is accomplished by means of the enamel, metal coating or varnishpreviously mentioned. If a metal coat is utilized, it should, of course,be interrupted by the insulating sealing material so that there will beno path between the two leads 6 over the outer surface of the container.

Fig. 8 illustrates a modification in which the electrode 5 is notcompletely enclosed by the ceramic portion 3, but in which the electrode5 partly protrudes into the glass tubing I. The sealing is made wit-henamel, metal coating, or varnish 4 as previously mentioned.

Fig. 9 shows a design where electrode 5 is located entirely within theglass vessel I and is supported by a tubular piece I0, which widens inthe direction of the discharge and protects the electrode and the glassagainst thermal action.

the inner metal coat known, some ceramic Spiral rod I4, secured .bycement I3, protects the leads 6, which pass through rod I4 and aresoldered at the end I5. I

Fig. l0v shows a case where two electrodes 5 are located in a ceramicvbody I. Theceramic body has no current leads and constitutes thedischarge tube. Another ceramic body 3, which has current leads andelectrodes 5, closes the discharge tube. The sealing is done by means ofenamel or metal coating or a varnish 4. When metal coating is used, itshould be interrupted by insulating sealing material.

It will be noted that the various embodiments of the invention disclosedin the drawing provide a container wall of ceramic material adjacent theelectrode or electrodes that is especially capable of withstandingstrong electric, chemical, and thermal effects. In particular, thelateral extensions from the ceramic portion for the purpose of sealingto the glass portion of the vessel, pro- ,vide a protection to the sealby the interposition of the rim of the ceramic portion between this sealand the discharge path. The conical sh'ape of the rim in Figs. 3 and 9provide means for concentrating the discharge towards the active surfaceof the electrode. The dielectric strength of a ceramic material permitsthe condenser electrode, illustrated in Fig. 6. Many modifications ofthe invention will, of course, be apparent to those skilled in the artfrom the foregoing description and the numerous embodiments illustrated.It is for this reason that the electrode 5 in most of the illustrationshas been only diagrammatically illustrated because the invention can beadapted to t in with the many structures disclosed in the prior art.

Whatis claimed:

1. An electric discharge device comprising a container having acup-shaped ceramic portion, a conductor passing through and in contactwith the ceramic bottom of said cup-shaped ceramic portion, and anelectrode within said cup-shaped ceramic portion connected with saidconductor, said container having another portion adjacent saidcup-shaped ceramic portion sealed thereto, said cup-shaped ceramicportion having its rim projecting past the sealed connection of said twoportions to within said other portion.

2. An electric discharge device comprising a cup-shaped ceramic portion,an electrode within said cup-shaped ceramic portion, a connection tosaid electrode passing through and in contact with the ceramic bottom ofsaid cup-shaped ceramic portions, a lateral extension from saidcup-shaped ceramic portion, and a container wall sealed to said lateralextension.

3. An electric discharge devicefcomprising a cup-shaped ceramic portion,an electrode within said cup-shaped ceramic portion, a connection tosaid electrode passing through and in contact with the ceramic bottom ofsaid cup-shaped ceramic portions, a lateral extension from. saidcup-shaped ceramic portion, and a container Wall sealed to said lateralextension, and a gastight coating on the exterior of said ceramicportion.

4. An electric discharge device comprising a container having acup-shaped ceramic portion, an electrode within said cup-shaped ceramicportion, a lead for said electrode, a lateral extension from saidcup-shaped ceramic portion, and a wall of said container sealed to saidlateral extension, said cup-shaped ceramic portion having a projectingconical rim. y

HUBERT WENDLIK.

